The International Cessna^® 170 Association

Can anyone kindly explain to me the difference between NAS and AN hardware?
Thanks, Sundby

NAS is short for National Aeronautical Standards. AN is short for Army-Navy Standards. and MS is short for Military Standards.

In short they are all standards to which the particular hardware is made to. I believe AN is the oldest standard which is being replaced by MS. Don't know the history of NAS.

I guess the better question is can AN be used where NAS is listed, for example, the landing gear axel bolts?
Thanks, Sundby

The NAS bolts are stronger than AN bolts. The NAS are about 160,000psi (tensile) vs. about 125,000psi for the AN bolts. I NAS bolts are optional for ski installation otherwise you can use AN hardware on the axles.

The development of aircraft special hardware needs was identified by the army and the navy in the early part of last century, and a joint committee known as the "Army-Navy" aviation standards commitee worked out a mutually agreed standard which became known as the "Army/Navy" or "AN" standard. It described materials and fit specifications for aircraft hardware. As Aircraft became more sophisticated (and as the military services each became more involved in aviation) the standard was revised to include certain additional specialized fasteners, and a new standard known as the "Military Specification/Standard" or "MS" standard. As commercial aviation developed specialized needs for aircraft use, the "National Aerospace Standard" or "NAS" standard was defined.
Generally, AN bolts are approved for most applications, and most AN hardware also has "MS" definitions as well. The NAS hardware is usually more specialized, and almost always refers to hardware with higher strength materials and/or closer fit tolerances than ordinary AN/MS hardware. For that reason is is also more expensive.

Common AN bolts are acceptable and specified for axle attachment, but NAS bolts are also approved substitutes, and are stronger, therefore sometimes recommended for more rigorous applications. Typically, NAS bolts cost 4 to 5 times as much as AN.

An excellent article on (mostly AN) Aircraft Hardware can be found at:
http://www.sportair.org/articles/5Aircr ... 0Know.html

George Et-al,
This maybe old news however the Genuine Aircraft Hardware Company offers, for $6.00, their Reference Catalog, which I have found to be a valuable Aircraft Hardware Reference. Last Christmas I bought a few to give to fellow aircraft geeks. Below is a link to the pertinant section of Aircraft Hardware's WEB site.

http://www.gen-aircraft-hardware.com/si ... _a_Catalog

A few of the reason for the higher cost of NAS is that many of the fasteners are "close tolerance, the threads are "rolled" instead of machine cut and of course they are of greater strength. (The rolled threading does two things. One, it adds surface density, and two, eliminates a sharp stress riser at the ends of "cut " threads.) Surface coatings are also more meaningful in NAS fasteners.

In the '60s I worked for Bendix Aerospace where we made stuff to go far out into space. A "never fail" policy was paramount. You don't spend millions sending a unit to map distant planets and depend on average technology to give 110%. I wouldn't worry about AN hardware holding the rollers in my seat frames but I want my wing spars and gear legs and axle to gear leg bolts, to be the highest quality I can buy. Look for the "dished" head and you will have a NAS bolt.

Would it be a AN, MS, or NAS set of vice-grips on that battery terminal, Gar?

I was wondering? Was it AN, MS, NAS or maybe a lot of plan old CRAP in Gars fuel system which made it run so well?

(It's going to be a loooonngg year for Gar till he can get his plane out somewhere.)

It was NASty, ANd it was MySterious.